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"""Diagnostic functions, mainly for use when doing tech support.""" |
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__license__ = "MIT" |
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import cProfile |
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from io import BytesIO |
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from html.parser import HTMLParser |
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import bs4 |
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from bs4 import BeautifulSoup, __version__ |
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from bs4.builder import builder_registry |
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from typing import ( |
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Any, |
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IO, |
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List, |
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Optional, |
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Tuple, |
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TYPE_CHECKING, |
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) |
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if TYPE_CHECKING: |
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from bs4._typing import _IncomingMarkup |
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import pstats |
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import random |
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import tempfile |
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import time |
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import traceback |
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import sys |
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def diagnose(data: "_IncomingMarkup") -> None: |
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"""Diagnostic suite for isolating common problems. |
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:param data: Some markup that needs to be explained. |
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:return: None; diagnostics are printed to standard output. |
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""" |
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print(("Diagnostic running on Beautiful Soup %s" % __version__)) |
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print(("Python version %s" % sys.version)) |
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basic_parsers = ["html.parser", "html5lib", "lxml"] |
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for name in basic_parsers: |
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for builder in builder_registry.builders: |
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if name in builder.features: |
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break |
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else: |
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basic_parsers.remove(name) |
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print( |
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("I noticed that %s is not installed. Installing it may help." % name) |
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) |
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if "lxml" in basic_parsers: |
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basic_parsers.append("lxml-xml") |
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try: |
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from lxml import etree |
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print(("Found lxml version %s" % ".".join(map(str, etree.LXML_VERSION)))) |
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except ImportError: |
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print("lxml is not installed or couldn't be imported.") |
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if "html5lib" in basic_parsers: |
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try: |
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import html5lib |
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print(("Found html5lib version %s" % html5lib.__version__)) |
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except ImportError: |
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print("html5lib is not installed or couldn't be imported.") |
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if hasattr(data, "read"): |
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data = data.read() |
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for parser in basic_parsers: |
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print(("Trying to parse your markup with %s" % parser)) |
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success = False |
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try: |
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soup = BeautifulSoup(data, features=parser) |
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success = True |
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except Exception: |
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print(("%s could not parse the markup." % parser)) |
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traceback.print_exc() |
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if success: |
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print(("Here's what %s did with the markup:" % parser)) |
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print((soup.prettify())) |
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print(("-" * 80)) |
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def lxml_trace(data: "_IncomingMarkup", html: bool = True, **kwargs: Any) -> None: |
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"""Print out the lxml events that occur during parsing. |
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This lets you see how lxml parses a document when no Beautiful |
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Soup code is running. You can use this to determine whether |
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an lxml-specific problem is in Beautiful Soup's lxml tree builders |
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or in lxml itself. |
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:param data: Some markup. |
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:param html: If True, markup will be parsed with lxml's HTML parser. |
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if False, lxml's XML parser will be used. |
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""" |
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from lxml import etree |
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recover = kwargs.pop("recover", True) |
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if isinstance(data, str): |
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data = data.encode("utf8") |
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if not isinstance(data, IO): |
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reader = BytesIO(data) |
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for event, element in etree.iterparse(reader, html=html, recover=recover, **kwargs): |
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print(("%s, %4s, %s" % (event, element.tag, element.text))) |
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class AnnouncingParser(HTMLParser): |
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"""Subclass of HTMLParser that announces parse events, without doing |
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anything else. |
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You can use this to get a picture of how html.parser sees a given |
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document. The easiest way to do this is to call `htmlparser_trace`. |
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""" |
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def _p(self, s: str) -> None: |
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print(s) |
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def handle_starttag( |
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self, |
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name: str, |
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attrs: List[Tuple[str, Optional[str]]], |
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handle_empty_element: bool = True, |
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) -> None: |
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self._p(f"{name} {attrs} START") |
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def handle_endtag(self, name: str, check_already_closed: bool = True) -> None: |
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self._p("%s END" % name) |
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def handle_data(self, data: str) -> None: |
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self._p("%s DATA" % data) |
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def handle_charref(self, name: str) -> None: |
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self._p("%s CHARREF" % name) |
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def handle_entityref(self, name: str) -> None: |
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self._p("%s ENTITYREF" % name) |
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def handle_comment(self, data: str) -> None: |
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self._p("%s COMMENT" % data) |
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def handle_decl(self, data: str) -> None: |
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self._p("%s DECL" % data) |
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def unknown_decl(self, data: str) -> None: |
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self._p("%s UNKNOWN-DECL" % data) |
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def handle_pi(self, data: str) -> None: |
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self._p("%s PI" % data) |
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def htmlparser_trace(data: str) -> None: |
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"""Print out the HTMLParser events that occur during parsing. |
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This lets you see how HTMLParser parses a document when no |
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Beautiful Soup code is running. |
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:param data: Some markup. |
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""" |
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parser = AnnouncingParser() |
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parser.feed(data) |
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_vowels: str = "aeiou" |
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_consonants: str = "bcdfghjklmnpqrstvwxyz" |
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def rword(length: int = 5) -> str: |
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"""Generate a random word-like string. |
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:meta private: |
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""" |
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s = "" |
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for i in range(length): |
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if i % 2 == 0: |
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t = _consonants |
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else: |
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t = _vowels |
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s += random.choice(t) |
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return s |
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def rsentence(length: int = 4) -> str: |
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"""Generate a random sentence-like string. |
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:meta private: |
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""" |
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return " ".join(rword(random.randint(4, 9)) for i in range(length)) |
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def rdoc(num_elements: int = 1000) -> str: |
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"""Randomly generate an invalid HTML document. |
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:meta private: |
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""" |
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tag_names = ["p", "div", "span", "i", "b", "script", "table"] |
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elements = [] |
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for i in range(num_elements): |
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choice = random.randint(0, 3) |
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if choice == 0: |
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tag_name = random.choice(tag_names) |
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elements.append("<%s>" % tag_name) |
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elif choice == 1: |
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elements.append(rsentence(random.randint(1, 4))) |
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elif choice == 2: |
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tag_name = random.choice(tag_names) |
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elements.append("</%s>" % tag_name) |
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return "<html>" + "\n".join(elements) + "</html>" |
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def benchmark_parsers(num_elements: int = 100000) -> None: |
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"""Very basic head-to-head performance benchmark.""" |
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print(("Comparative parser benchmark on Beautiful Soup %s" % __version__)) |
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data = rdoc(num_elements) |
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print(("Generated a large invalid HTML document (%d bytes)." % len(data))) |
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for parser_name in ["lxml", ["lxml", "html"], "html5lib", "html.parser"]: |
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success = False |
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try: |
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a = time.time() |
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BeautifulSoup(data, parser_name) |
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b = time.time() |
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success = True |
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except Exception: |
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print(("%s could not parse the markup." % parser_name)) |
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traceback.print_exc() |
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if success: |
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print(("BS4+%s parsed the markup in %.2fs." % (parser_name, b - a))) |
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from lxml import etree |
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a = time.time() |
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etree.HTML(data) |
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b = time.time() |
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print(("Raw lxml parsed the markup in %.2fs." % (b - a))) |
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import html5lib |
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parser = html5lib.HTMLParser() |
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a = time.time() |
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parser.parse(data) |
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b = time.time() |
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print(("Raw html5lib parsed the markup in %.2fs." % (b - a))) |
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def profile(num_elements: int = 100000, parser: str = "lxml") -> None: |
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"""Use Python's profiler on a randomly generated document.""" |
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filehandle = tempfile.NamedTemporaryFile() |
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filename = filehandle.name |
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data = rdoc(num_elements) |
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vars = dict(bs4=bs4, data=data, parser=parser) |
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cProfile.runctx("bs4.BeautifulSoup(data, parser)", vars, vars, filename) |
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stats = pstats.Stats(filename) |
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stats.sort_stats("cumulative") |
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stats.print_stats("_html5lib|bs4", 50) |
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if __name__ == "__main__": |
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diagnose(sys.stdin.read()) |
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